Disruption of nuclear envelope integrity as a possible initiating event in tauopathies.

The microtubule-associated protein tau is an abundant component of neurons of the central nervous system. In Alzheimer's disease and other neurodegenerative tauopathies, tau is found hyperphosphorylated and aggregated in neurofibrillary tangles. To obtain a better understanding of the cellular perturbations that initiate tau pathogenesis, we performed a CRISPR-Cas9 screen for genetic modifiers that enhance tau aggregation. This initial screen yielded three genes, BANF1, ANKLE2, and PPP2CA, whose inactivation promotes the accumulation of tau in a phosphorylated and insoluble form. In a complementary screen, we identified three additional genes, LEMD2, LEMD3, and CHMP7, that, when overexpressed, provide protection against tau aggregation. The proteins encoded by the identified genes are mechanistically linked and recognized for their roles in the maintenance and repair of the nuclear envelope. These results implicate the disruption of nuclear envelope integrity as a possible initiating event in tauopathies and reveal targets for therapeutic intervention.

Efficient engraftment and viral transduction of human hepatocytes in an FRG rat liver humanization model.

Humanized liver rodent models, in which the host liver parenchyma is repopulated by human hepatocytes, have been increasingly used for drug development and disease research. Unlike the leading humanized liver mouse model in which Fumarylacetoacetate Hydrolase (Fah), Recombination Activating Gene (Rag)-2 and Interleukin-2 Receptor Gamma (Il2rg) genes were inactivated simultaneously, generation of similar recipient rats has been challenging. Here, using Velocigene and 1-cell-embryo-targeting technologies, we generated a rat model deficient in Fah, Rag1/2 and Il2rg genes, similar to humanized liver mice. These rats were efficiently engrafted with Fah-expressing hepatocytes from rat, mouse and human. Humanized liver rats expressed human albumin and complement proteins in serum and showed a normal liver zonation pattern. Further, approaches were developed for gene delivery through viral transduction of human hepatocytes either in vivo, or in vitro prior to engraftment, providing a novel platform to study liver disease and hepatocyte-targeted therapies.

Some attenuated variants of vesicular stomatitis virus show enhanced oncolytic activity against human glioblastoma cells relative to normal brain cells.

Vesicular stomatitis virus (VSV) has been shown in laboratory studies to be effective against a variety of tumors, including malignant brain tumors. However, attenuation of VSV may be necessary to balance the potential toxicity toward normal cells, particularly when targeting brain tumors. Here we compared 10 recombinant VSV variants resulting from different attenuation strategies. Attenuations included gene shifting (VSV-p1-GFP/RFP), M protein mutation (VSV-M51), G protein cytoplasmic tail truncations (VSV-CT1/CT9), G protein deletions (VSV-dG-GFP/RFP), and combinations thereof (VSV-CT9-M51). Using in vitro viability and replication assays, the VSV variants were grouped into three categories, based on their antitumor activity and non-tumor-cell attenuation. In the first group, wild-type-based VSV-G/GFP, tumor-adapted VSV-rp30, and VSV-CT9 showed a strong antitumor profile but also retained some toxicity toward noncancer control cells. The second group, VSV-CT1, VSV-dG-GFP, and VSV-dG-RFP, had significantly diminished toxicity toward normal cells but showed little oncolytic action. The third group displayed a desired combination of diminished general toxicity and effective antitumor action; this group included VSV-M51, VSV-CT9-M51, VSV-p1-GFP, and VSV-p1-RFP. A member of the last group, VSV-p1-GFP, was then compared in vivo against wild-type-based VSV-G/GFP. Intranasal inoculation of young, postnatal day 16 mice with VSV-p1-GFP showed no adverse neurological effects, whereas VSV-G/GFP was associated with high lethality (80%). Using an intracranial tumor xenograft model, we further demonstrated that attenuated VSV-p1-GFP targets and kills human U87 glioblastoma cells after systemic application. We concluded that some, but not all, attenuated VSV mutants display a favorable oncolytic profile and merit further investigation.